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...effects on vegetable dyes and other properties) and the concentration of hydrogen ions in the solution. Correspondingly, basic (or alkaline) properties could then be associated with the presence of
hydroxide ions (OH
−) in aqueous solution, and the neutralization of acids by bases could be explained in terms of the reaction of these two ions to give the neutral molecule water...

...carbonium ions. The soft acids include cuprous, silver, mercurous, and the halogen cations. Typical soft bases are iodide, thiocyanate, sulfide, and triphenylphosphine; whereas hard bases include hydroxide, fluoride, and many oxyanions. The dividing line between the hard and soft categories is not a sharp one, and its theoretical interpretation is obscure. Nevertheless, a surprising amount of...

bases

...(sulfuric acid), HNO
3 (nitric acid), and H
3PO
4 (phosphoric acid). Bases, on the other hand, are proton acceptors. The most common base is the
hydroxide ion (OH
−), which reacts with an H
+ ion to form a water molecule.
H+ + OH− → HOH (usually written...